Traditional automatic dishwashing detergent formulations containing phosphate, and more particularly sodium tripolyphosphate (STPP), have proven to be effective for general cleansing of dishware as well as avoiding filming and spotting of dishware. Recent legislation requiring the removal of phosphate-based builders from automatic dishwashing detergents has created numerous formulation challenges. While some substitutes for STPP have demonstrated relatively effective cleaning, they tend to be less than optimal regarding spotting and/or filming.
In order to compensate for spotting and filming, formulators have supplemented phosphate-free compositions with sulfonated dispersant polymers and other additives which are designed to prevent redeposition of soils and precipitation in the wash water onto dishware. However, it has been found that not all substrates in the wash show the same results. For example, some formulations may prevent spotting on glass, but may have poor performance regarding filming on plastic. Accordingly, preventing filming and spotting on dishware in the absence of phosphorus-based cleaning products has proven to be difficult.
Based on the foregoing, there is a need for a rinse aid which provides acceptable filming and spotting on dishware in the absence of phosphorus-containing elements.